Exposure device for exposing a transparent photographic original

ABSTRACT

The invention relates to an exposure device for exposing a transparent photographic original and reproducing said photographic original on photosensitive material. The exposure device has a first light source comprising a number of elements that emit light of different spectral bands, whose light strikes the photographic original along a first optical path or can be directed onto the photographic original using optical elements. The exposure device has additional real and/or virtual light sources, whose light strikes the photographic original along additional optical paths, or can be directed onto the photographic original using optical elements. The light that falls along the additional optical paths strikes the photographic original at different angles from the angle of incidence of the first optical path.

[0001] The invention is based on an exposure device to expose atransparent photographic original based on the overall concept of Patentclaims 1 and 2.

[0002] Such an exposure device is known, for example, from the EuropeanPatent no. EP 0 691 568. This patent describes a matrix composed of red,green, and blue LED elements that is used to expose photographic film toproject the image onto photographic paper or onto a plane-surfacesensor. As is usual with conventional light sources that expose andproject transparent originals, the light of an LED matrix is scatteredby a scatter plate in various directions. The scatter plate causes thelight to be softer, so that scratches or other defects present in thephotographic original are not reproduced, or are reproduced at a reducedlevel.

[0003] A disadvantage of such a scatter plate, positioned after theexposure device, is that it scatters a large portion of the lightemitted from the LED away from the image, thus enormously reducing theefficiency of the light source, so that the exposure time for theprojection is greatly increased. that the exposure time for theprojection is greatly increased.

[0004] The German Patent Application No. DE 100 41 750 (not yetpublished) also describes an exposure device in which images to bescanned are illuminated using LED matrices. Each LED matrix includesLED's of different colors, and the light from several matrices iscombined via a beam splitter into an illumination beam path to createthe image of the photographic original.

[0005] This scanner contains no scatter medium to convert the light intosoft light, so that defects present in the photographic original arereproduced without limitation in the recorded image data. Therefore, thepatent document claims a correction process to correct these reproduceddefects. Such defect-correction processes are very computer-timeintensive, particularly if many defects are present, so that rapidprocessing of the recorded image signals is not possible using adefect-correcting scanner. photographing, processing, or imagereproduction process are undesirable.

[0006] It is therefore the objective of this invention to configure ascanner or printer in such a manner that the processing of the images tobe reproduced may occur as quickly as possible without detraction fromthe image quality, particularly detraction caused by the reproduction ofdefects. This should be realizable with relatively low cost.

[0007] This objective is achieved by an exposure device to expose atransparent image using a printer or scanner based on thecharacteristics of Patent claim 1 or 2.

[0008] According to the invention, a transparent photographic originalis illuminated from several directions for the purpose of projectionwhereby the light strikes the image along differing optical paths. Eachpoint of the photographic original is struck by light arriving atdifferent incident angles. The light arriving at different incidentangles can be combined onto the photographic original, but it is moreadvantageous for quick processing for the photographic original to beilluminated simultaneously from different directions.

[0009] The light emitted from the primary light source serves to projectthe image content of the photographic original onto light-sensitivematerial or an electronic receptor device. For the projection oftransparent color photographic originals, light emitters emitting lightin different bands of the spectrum are provided. The light emitted fromthem strikes either directly along the first optical path onto thephotographic original, or is directed onto the photographic original bymeans of illumination optics consisting of additional optical elements,such as condenser lenses or mirrors.

[0010] Based on the invention, other light sources are provided, inaddition to this primary light source, that serve to illuminate thephotographic original. The additional light sources may be actual lightsources, or actual light-emitting sources, or the additional lightsources may be virtual light sources. Virtual light sources may includemirrors or beam splitters that reflect the light of an actual lightsource. The light from additional actual and/or virtual light sourcesstrikes at an incident angle differing from that of the primary lightsource onto the photographic original. It is particularly advantageousif several additional actual and/or virtual light sources are providedwhose light strikes the photographic original at several differentincident angles.

[0011] The light from the primary light source projects the imageinformation located on the photographic original onto light-sensitivematerial or onto a recording device. If, however, defects such asscratches or dust are present on the photographic original, the lightfrom this light source is diffracted, scattered, or reflected. Thediverted light no longer strikes the entry pupil of the projectingoptics, and cannot reach the light-sensitive material or recordingdevice. Thus, the light from the primary light source which strikes thedefects in the photographic original is not projected, or is onlypartially projected, onto the light-sensitive material or recordingdevice, and the image information is only incompletely reproduced. Areaswith dark defects or incomplete image information corresponding to thedefects are the result in the projected image. strikes the defects inthe photographic original is not projected, or is only partiallyprojected, onto the light-sensitive material or recording device, andthe image information is only incompletely reproduced. Areas with darkdefects or incomplete image information corresponding to the defects arethe result in the projected image.

[0012] In contrast, the light from additional actual and/or virtuallight sources strikes the photographic original at an incident angledifferent from that of the primary light source, and, afterstraight-line penetration of the photographic original, does not strikethe entry pupil of the projecting optics. No image information from theadditional actual and/or virtual light sources is projected onto thelight-sensitive material or recording device unless this light isdeflected in some manner. This is exactly what happens at the sites ofdefects. At the defective sites of the photographic original at whichthe light from the primary light source is deflected away from the entrypupil, the light striking the entry pupil of the projecting optics at adifferent incident angle is split, scattered, or reflected. Thus, thelight from an additional actual and/or virtual light source thatilluminated the photographic original at suitable incident angles passesthrough the recording optics and thus onto the light-sensitive materialor correspondingly onto the recording device, thus transferring theimage information present at the defect site. The image information fromthe primary light source missing in the reproduction is replaced byimage information projected from the additional actual and/or virtuallight sources. Thus, defective sites in the photographic original may beso illuminated that they are not visible in the recording, or at leasthave reduced effect. Since defects occur in different forms andorientations, various incident angles are required to reduce theireffects by means of light entering the entry pupil after diffraction,scattering, and/or reflection. In order, therefore, not to reproduceall, or as many as possible, defects in the projection, it is necessarythat light strike the photographic original from as many differentincident angles as possible. Therefore, several additional actual and/orvirtual light sources are provided that illuminate the photographicoriginal at various incident angles. Since the defect sites may extendin various directions on the photographic original, and since thedeflection of incident light as a rule is only effective ifperpendicular to the orientation direction of the defect, it isadvantageous to position additional actual and/or virtual light sourcesdistributed spatially around the primary light source. In order toreduce or correct as many defect sites in the reproduction as possible,it would be ideal to configure a Lambert beam using additional lightsources. The number of light sources required for this does notrepresent unmanageable expense or unreasonable cost.

[0013] It has been shown that defects are essentially caused byscratches to the photographic original or dust particles lying on thephotographic original. Also, scratches, particularly to photographicfilm, generally occur along one direction, the so-called film traveldirection. Most defects caused by these scratches are reduced in thatlight from additional actual and/or virtual light sources strikes thephotographic original at an incident angle not much different from thatof the primary light source. In an advantageous embodiment of theexposure device, additional actual and/or virtual light sources are sopositioned that light emitted from them along the optical axis does notpass directly through the entry pupil of the projecting optics, and theincident angle of this light onto the photographic original deviates asmall amount from the incident angle of the primary light source. Thus,the incident angle of additional actual and/or virtual light sources isnaturally dependent on entry pupil and positioning of the projectingoptics. The additional light sources are preferably so positioned thattheir light strikes the photographic original at an incident angle ofless than 40° to the incident angle of the primary light source. If, forexample, the light from the primary light source strikes thephotographic original at the perpendicular, then the incident angle ofadditional actual and/or virtual light sources will advantageously liebetween 55° and 75°, i.e., about 65° . Error sites caused by scratchesin the photographic original of the photograph are reduced the mostefficiently by means of additional actual and/or virtual light sourcesso positioned.

[0014] The additional actual and/or virtual light sources shouldpreferably be positioned on both sides of the primary light source, oraround it spatially, so that reduction in the defect sites issymmetrical. The additional actual and/or virtual light sources arepreferably positioned perpendicular to the travel direction of thescratches in the photographic original. For photographic film, thistravel direction as a rule is the same as the film travel direction inwhich the film is moved through a processing machine or contact-sheetprinter.

[0015] In contrast, error sites in the image caused by dust or othercontaminating particles on the photographic original or on thesupporting surface of the photographic original, are reduced mostefficiently by having the light from additional actual and/or virtuallight sources strike the photographic original at a very flat incidentangle. Thus, the light partially strikes the underside of the dustparticle, is reflected by it, and passes into the entry pupil of theprojecting optics, while the light from the primary light source isabsorbed by or reflected back by the dust particle. Therefore, theactual and/or virtual light sources are advantageously so positionedthat their light strikes the photographic original at an incident angle<50° . The selected incident angle is preferably between 45° and 25°, aslimited by design considerations.

[0016] It is thus not necessary to create a complete Lambert beamcharacteristic by means of actual and/or virtual light sources. Forreduction of defect sites in the projection caused by defect sites orparticles on the photographic original, it is sufficient to positionactual and/or virtual light sources in selectively-determined lightincidence angles. In an advantageous embodiment, additional actualand/or virtual light sources are positioned at an angle only slightlydeviating from that of the original, and also additional light sourcesarranged with a very flat Incidence angle to the photographic original.Additional actual and/or virtual light sources that are positioned atdifferent angles might reduce the defect sites, but their efficiency isso low that the cost is not justified by the improvement to the image.

[0017] Since the light from additional actual and/or virtual lightsources reaches the entry pupil of the projecting optics onlyindirectly, i.e., via diffraction, scattering, or reflection, theintensity of the light projected from these light sources onto therecording device is very low. Therefore, relatively long exposure timesare necessary in order to completely reproduce the image informationlost because of the defect sites. Long exposure times, however, are veryundesirable with high-output printers or scanners. It is thereforeparticularly advantageous to make the use of additional actual and/orvirtual light sources dependent on the condition of the photographicoriginal, or on the number and properties of the defect sites on thephotographic original. If, for example, a seriously-scratchedphotographic original must be used, it is worthwhile, to illuminateusing the light from additional actual and/or virtual light sourcespositioned near the primary light source. If, on the other hand, thephotographic original is very dirty, it is preferable to illuminateusing light sources at a flat angle. A photographic original influencedvery little by defects may also be advantageously illuminated withoutthe additional actual and/or virtual light sources. For this reason, itis very advantageous for the additional actual and/or virtual lightsources to be switchable depending on the condition of the photographicoriginal.

[0018] The condition of the photographic original may be evaluated as,for example, a lightly-scratched first copy of a photographic film, orperhaps a subsequent order from a defective original. It is alsopossible using a so-called pre-scan to sample the photographic originalin order to establish whether the photographic original is seriouslyinfluenced by defects or not. The pre-scan may be performed, forexample, using a coarse infrared scan. For this, it is sufficient toilluminate the photographic original with very oblique infrared lightwhich does not normally enter the entry pupil of the projecting optics,and to measure which portion of the infrared radiation diffracted orscattered at the defect site reaches the recording device. Based on thispre-scan, a subsequent scan or illumination of the photographic originalmay be performed using only the light from the primary light source, orwith only the light from the primary and selected additional actualand/or virtual light sources.

[0019] The primary light source of the exposure device preferablyincludes multi-colored LED's. These LED's include the red, green, andblue bands of the spectrum for the scanning or copying of transparentcolor photographic originals. If a procedure is to be used to correctremaining defect sites, it is advantageous to provide infrared LED's.These LED's may be mixed in a matrix-like array. It is also advantageousto position LED's from different bands of the spectrum, or for a portionof the band of the spectrum, in one array and others in a second array.The light from the different arrays may be combined, for example, via abeam splitter into a single beam path. It is also possible to mix thelight from different LED matrices in a light mixer and subsequently todirect it into one beam path onto the photographic original. Inprinciple, all light sources suitable for the illumination oftransparent color photographic originals independent of their structureare conceivable and suitable.

[0020] Additional actual light sources will preferably includerapidly-switchable color light emitters such as LED's. It is desirablethat the spectral band of these additional actual light sources tocoincide with that of the spectral band covered by the primary lightsource. The infrared band of the spectrum, which is used merely forscratch correction, need not be covered by the additional actual lightsources. If this is not the case, the difference in the exposure timeselected for the additional actual light sources must be calculatedbased on the sensitivity of the recording device.

[0021] The additional actual and/or virtual light sources are sostructured that the light emitted from them strikes the photographicoriginal at an angle deviating slightly from the incident angle of theprimary light source. As a rule, an angle of 90° is selected forstandard illumination of the photographic original. Therefore, theadditional actual and/or virtual light sources are so positioned thatthe incident angle of their light is less than 90°.

[0022] Several additional actual and/or virtual light sources arepreferably provided that illuminate the photographic original fromdifferent angles.

[0023] In a particularly advantageous arrangement, the light sources areso structured or so positioned that their optical axis does not passthrough the entry pupil of the projecting optics. The straight-linelight emitted from the additional actual and/or virtual light sources isthus not projected by the projecting optics onto the recording device orlight-sensitive material. Only if the light from additional actualand/or virtual light sources strikes a defect site in the photographicoriginal can it be so deflected that it passes through the entry pupilof the projecting optics.

[0024] In order to ensure that the reduction in defect sites in theimage data caused by defects is uniform in all regions of the image, itis advantageous to configure and position the additional actual and/orvirtual light sources so that they illuminate the photographic originaluniformly, i.e., the additional actual and/or virtual light sourcesshould preferably be projected overall onto each point of thephotographic original with the same intensity for each color. Each pointof the photographic original should be illuminated in all colors at thesame intensity.

[0025] Semi-conductor diodes or other light-emitting rapidly-switchableemitters may be used as primary or additional actual light sourcesinstead of LED's.

[0026] In order to avoid additional actual light sources, it isadvantageous to use mirrors instead of additional actual light sources,so that virtual light sources are created that shine the light from theprimary light source at an additional incident angle onto thephotographic original. This is of particular advantage if color-neutralmirror surfaces are used. If laterally-radiated light from the primarylight source is used for additional illumination, the fact that the bandof the spectrum of the additional light sources does not coincide withthe bands of the spectrum from the primary light source may bedisregarded. Because of the color neutrality of the mirror, coincidenceof the band of the spectrum of the additional virtual light sources withthe bands of the spectrum from the primary light source is ensured.

[0027] The above-mentioned use of light derived laterally from theprimary light source to control the virtual light sources that wouldotherwise be lost further results in energy savings and in reducedheating of the lamp housing. Additional cooling measures or large-volumelamp housings are not required.

[0028] In order to achieve uniform improvement of projection quality,the mirror surfaces are preferably arranged in a ring about the opticalaxis of the projecting optics of the photographic original.

[0029] An embodiment especially preferred is one where the mirrorsurfaces are so structured and positioned that the optical axis of thelight from the primary light source reflected from them does not passthrough the entry pupil of the optics forming the photographic original

[0030] Instead of a mirror, beam splitters or other optical elements areconceivable. Important is only the fact that virtual light sources arecreated which fulfill advantageous conditions for the additional lightsources.

[0031] Further details, advantages, and properties of the invention maybe taken from the embodiment examples represented in the followingillustrations, which show:

[0032]FIG. 1 a schematic representation of a first embodiment example ofa scanner with an illumination device based on the invention, and

[0033]FIG. 2 a schematic representation of another embodiment example ofa scanner with an illumination device based on the invention.

[0034]FIG. 1 shows a scanner to project transparent photographicoriginals onto a recording device with additional actual light sources.An exposure device 1 illuminates the transparent photographic originals2, i.e., a photographic film, in order to project it onto the recordingdevice 3. The exposure device 1 includes a LED array 4 in which LED's ofdifferent colors are mixed in a matrix. Red, green, and blue LED's arepreferably included. If a scratch correction via infrared light is to beperformed, additional infrared LED's are provided. A lens array 5 ispositioned in front of

[0035] The recording device 3 includes three CCD chips 10, 11, and 12that convert the three spectral portions of the light into electricalimage signals. These spectral portions are separated from the overallprojection beam path via beam splitters 13 and 14. If an additional scanin infrared light is planned, it is worthwhile to provide an additionalCCD chip by means of which the infrared light is also separated from thecommon beam path.

[0036] According on the invention, additional light sources 15, 16, 17and 18 are provided to project the image whose emitted light strikes thephotographic original along an optical path different from that of theprimary light source. The light sources 16 and 17 are so positioned thattheir light strikes the photographic original at an angle of about 65°.An incident angle of about 35° is selected for the light sources 15 and18. An incident angle of about 35° is selected for the light sources 15and 18. The other light sources are structured exactly as the primarylight source 1. Many worthwhile configurations are conceivable, however.

[0037] Important is only that the spectral colors emitted from theadditional actual light sources coincide with those from the Therecording device 3 includes three CCD chips 10, 11, and 12 that convertthe three spectral portions of the light into electrical image signals.These spectral portions are separated from the overall projection beampath via beam splitters 13 and 14. If an additional scan in infraredlight is planned, it is worthwhile to provide an additional CCD chip bymeans of which the infrared light is also separated from the common beampath.

[0038] According on the invention, additional light sources 15, 16, 17and 18 are provided to project the image whose emitted light strikes thephotographic original along an optical path different from that of theprimary light source. The light sources 16 and 17 are so positioned thattheir light strikes the photographic original at an angle of about 65° .An incident angle of about 35° is selected for the light sources 15 and18. An incident angle of about 35° is selected for the light sources 15and 18. The other light sources are structured exactly as the primarylight source 1. Many worthwhile configurations are conceivable, however.

[0039] Important is only that the spectral colors emitted from theadditional actual light sources coincide with those from the primarylight source. The additional actual light sources may be so positionedthat their light also passes through the condenser lens 7. They may,however, be so positioned that their light passes between the condenserlens and the film stage, and strikes directly onto the image. It is alsopossible to omit the condenser lens 7 completely. In this case, thelight yield of the scanner is reduced.

[0040] Use of additional actual light sources ensures that each point ofthe photographic original is illuminated from different light sources atdifferent angles. While the light from the light source 1 strikes thephotographic perpendicularly, passes through it, and ends up directly onthe recording device 13 via the entry pupil of the projecting optics 9,the light emitted from the additional actual light sources 15, 16, 17and 18 misses the entry pupil of the projecting optics 9 afterilluminating the photographic original. The light from additional actuallight sources does not strike the entry pupil of the projecting optics 9without the photographic original, or without passing through regularimage points of the photographic original, and thus does not reach therecording device 3 in a normal case.

[0041] There is thus no contribution to projection of the image locatedon the photographic original unless it strikes a defect site of thephotographic original. At defect sites of the photographic original ordust particles on the photographic original that have the effect ofabsorbers or cylindrical lenses, the light from the light sources isdiffracted, scattered, or reflected. This light deflection affects thelight of the first exposure device 1 in that it does not reach, or onlypartially reaches, the entry pupil of the projecting optics 9. Only alittle, or no, light strikes the recording device at the image pointformed by a defect site, and no error site is reproduced in the imagedata.

[0042] The light from additional actual light sources that normally doesnot enter the entry pupil is deflected and scattered at defect sites orscratches, and is scattered and reflected from absorbers if it strikesthem at the proper angle so that it enters the entry pupil and thus isprojected onto the recording device. This light may replace the lostlight from the primary light source 1, thus brightening defect sites inthe image caused by defects. This makes it possible to reduce the numberof defect sites caused by defects, and to obtain a defect-free image oran image with a reduced number of defects.

[0043]FIG. 2 shows another embodiment example of a scanner used toproject transparent photographic originals onto a recording device withadditional virtual light sources. As in FIG. 1, an exposure device 1illuminates the transparent photographic original 2 in order to projectit onto the recording device 3. For this, the exposure device 1 consistsof an LED array 4 in which various-colored LED's are positioned andmixed in a matrix, a lens array 5 that focuses the light primarilytoward the photographic original 2, and a color filter 6. The lightemitted from the exposure device 1 along the main illumination directionis projected onto the photographic original 2 located on the film stage8 via a condenser lens 7. The exposure light passing through thephotographic original 2 is subsequently projected onto the recordingdevice 3. The recording device 3 includes three CCD chips 10, 11, and 12that convert the three spectral components of the light into electricalimage signals. The spectral components are separated from the commonbeam path via beam splitters 13 and 14. Likewise, additional LED's forinfrared light as described for FIG. 1, or additional CD chips, may beprovided in the scanner.

[0044] According to the invention, additional virtual light sources 22,24, 26 and 28 are provided to expose the image. These virtual lightsources include mirrors that reflect the laterally-radiated light fromthe LED arrays of the exposure unit 1 and which are not used by theembodiment example described in FIG. 1, so that light passes alongadditional optical paths onto the photographic original 2. The mirrors24 and 26 are so positioned here that the light from the exposure source1 reflected from them strikes the photographic original at an angle ofabout 65°. The mirrors 22 and 28 are so positioned that an incidentangle of about 35° is achieved. The particular advantage in thisconfiguration is the fact that the spectral colors coincide with thosefrom the primary light source, since only the light from the exposureunit 1 is used. The virtual light sources 22, 24, 26, and 28 may therebybe so positioned that their light also passes through the condenser lens7, such as for example the light reflected from the mirrors 24 and 26.They may also be so positioned that their light passes between thecondenser lens 7 and the film stage 8, directly onto the photographicoriginal 2, such as the light reflected from mirrors 22 and 28.

[0045] Using a scanner, as described for FIGS. 1 and 2, colorphotographs may be reproduced via illumination of the photographicoriginal 2 from the light source 1 in all colors simultaneously. Theadditional actual and/or virtual light sources are switched on in orderto reduce defect sites, so that they form a non-defective image signalat the defect sites.

1. Exposure device to expose a transparent photographic original toproject a photographic original onto light-sensitive material, wherebythe exposure device includes a first light source with a number ofelements emitting light of different bands of the spectrum, whose lightstrikes the photographic original along a first optical path or may bedirected onto the photographic original by means of optical elements,characterized in that the exposure device includes additional actualand/or virtual light sources whose light strikes onto the photographicoriginal along additional optical paths or may be directed onto thephotographic original by means of optical elements, whereby the lighttraveling along the additional optical paths strikes the photographicoriginal at a different incident angle from the incident angle of thefirst optical path.
 2. Exposure device to expose a transparentphotographic original to reproduce the photographic original on arecording device to convert the light transmitted from the photographicoriginal into electrical image signals whereby the exposure deviceincludes a first light source with a number of elements emitting lightof different bands of the spectrum, whose light strikes the photographicoriginal along a first optical path or may be directed onto thephotographic original by means of optical elements, characterized inthat the exposure device includes additional actual and/or virtual lightsources whose light strikes onto the photographic original alongadditional optical paths or may be directed onto the photographicoriginal by means of optical elements, whereby the light traveling alongthe additional optical paths strikes the photographic original at adifferent incident angle from the incident angle of the first opticalpath.
 3. Exposure device according to claim 1 or 2, characterized inthat the incident angle of light from additional light sources deviatesfrom the incident angle of light from the primary light source by lessthan 40°.
 4. Exposure device according to claim 3, characterized in thatthe incident angle of light from additional light sources deviate bybetween 15° and 35° from the incident angle of light from the primarylight source.
 5. Exposure device according to claim 1 or 2,characterized in that the incident angles of light from additional lightsources are less than 50°.
 6. Exposure device according to claim 5,characterized in that the incident angles of light from additional lightsources lie between 45° and 25°.
 7. Exposure device according to claim 1or 2, characterized in that light sources include LED's.
 8. Exposuredevice according to claim 7, characterized in that LED's possessingdiffering bands of the spectrum from the primary light source arearranged in an array.
 9. Exposure device according to claim 7,characterized in that LED's possessing differing bands of the spectrumare arranged in a mixed configuration.
 10. Exposure device according toclaim 7, characterized in that LED's possessing differing bands of thespectrum of the additional light sources are arranged in an array. 11.Exposure device according to one of the prior claims, characterized inthat additional light sources may be switched on or off individually.12. Exposure device according to claim 1 or 2, characterized in thatadditional virtual light sources are formed from the light reflectedfrom the primary light source by mirror surfaces.
 13. Exposure deviceaccording to claim 12, characterized in that the mirror surfaces extendin a ring around the optical axis of the projecting optics of thephotographic original.
 14. Exposure device according to one of the priorclaims, characterized in that the band of the spectrum of the additionallight sources coincide with the bands of the spectrum from the primarylight source.
 15. Exposure device according to claim 14, characterizedin that the spectral band includes red, green, and blue.
 16. Exposuredevice according to claim 14, characterized in that the mirror surfacesare color-neutral.
 17. Exposure device according to one of the priorclaims, characterized in that the additional light sources are sostructured and positioned that their optical axis does not pass throughthe entry pupil of the optics projecting the photographic original. 18.Exposure device according to claim 17, characterized in that the mirrorsurfaces are so structured and positioned that the optical axis of thelight from the primary light source reflected from them does not passthrough the entry pupil of the optics projecting the photographicoriginal.
 19. Exposure device according to one of the prior claims,characterized in that the additional light sources are so structured andpositioned that they illuminate the photographic original uniformly inevery band of the spectrum.
 20. Exposure device according to one of theprior claims, characterized in that the additional light sources are sostructured and positioned that their light strikes every point of thephotographic original from several directions.